org.terrier.structures.postings

Class ANDIterablePosting

java.lang.Object

org.terrier.structures.postings.IterablePostingImpl

org.terrier.structures.postings.ANDIterablePosting

All Implemented Interfaces:

Closeable, AutoCloseable, IterablePosting, Posting

Direct Known Subclasses:

PhraseIterablePosting, ProximityIterablePosting

public class ANDIterablePosting
extends IterablePostingImpl

An instance of IterablePostings that works with passed arrays of ids and frequencies. The document must contain all of the terms in the query to be matched (AND)

Author:

Richard McCreadie

Field Summary

Fields

Modifier and Type	Field and Description
protected int	currentId
protected int	frequency
protected IterablePosting[]	ips
protected int	termCount

Fields inherited from interface org.terrier.structures.postings.IterablePosting

END_OF_LIST, EOL

Constructor Summary

Constructors

Constructor and Description
ANDIterablePosting(IterablePosting[] _ips, EntryStatistics[] _p)
ANDIterablePosting(IterablePosting[] _ips, Pointer[] _p)

Method Summary

Modifier and Type	Method and Description
WritablePosting	asWritablePosting() Copies this posting to one free of an iterator.
protected boolean	calculateFrequency() returns true if the document matches
void	close()
boolean	endOfPostings() Status method to see if this posting list iterator has been finished
int	getDocumentLength() Return the length of the document for this posting.
int	getFrequency() Return the frequency of the term in the current document
int	getId() Return the id of the current posting.
int	next() Move this iterator to the next posting.
int	next(int targetID) This implementation of next(int) which uses next()
void	setId(int id) It may be of benefit to update the frequency of the id in some applications.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

currentId

protected int currentId

ips

protected IterablePosting[] ips

termCount

protected final int termCount

frequency

protected int frequency

Constructor Detail

ANDIterablePosting

public ANDIterablePosting(IterablePosting[] _ips,
                          EntryStatistics[] _p)
                   throws IOException

Throws:

IOException

ANDIterablePosting

public ANDIterablePosting(IterablePosting[] _ips,
                          Pointer[] _p)
                   throws IOException

Throws:

IOException

Method Detail

getId

public int getId()

Description copied from interface: Posting

Return the id of the current posting. For the inverted index, this is the docid; for the direct index it corresponds to the term id

Returns:

id of the posting

getFrequency

public int getFrequency()

Description copied from interface: Posting

Return the frequency of the term in the current document

Returns:

frequency of posting, in tokens

getDocumentLength

public int getDocumentLength()

Description copied from interface: Posting

Return the length of the document for this posting. Usually uses the DocumentIndex, may do otherwise if document length statistics are in posting list

Returns:

length of the document of the current posting in tokens.

setId

public void setId(int id)

Description copied from interface: Posting

It may be of benefit to update the frequency of the id in some applications. This should not be used lightly, as it may break the decompression of other postings in iterators.

next

public int next(int targetID)
         throws IOException

Description copied from class: IterablePostingImpl

This implementation of next(int) which uses next()

Specified by:

next in interface IterablePosting

Overrides:

next in class IterablePostingImpl

Parameters:

targetID - id of the posting to find in this posting list.

Returns:

id of the posting found, or EOL if end of posting list.

Throws:

IOException

next

public int next()
         throws IOException

Description copied from interface: IterablePosting

Move this iterator to the next posting.

Returns:

id of next posting, or EOL if end of posting list

Throws:

IOException

calculateFrequency

protected boolean calculateFrequency()

returns true if the document matches

endOfPostings

public boolean endOfPostings()

Description copied from interface: IterablePosting

Status method to see if this posting list iterator has been finished

Returns:

true if next() or next(int) would return EOL or have returned EOL.

close

public void close()
           throws IOException

Throws:

IOException

asWritablePosting

public WritablePosting asWritablePosting()

Description copied from interface: Posting

Copies this posting to one free of an iterator. Kind of like a clone.

Returns:

an identical posting, but which can be maniulated free of this iterator